Patent Document 1 describes that 6-amino-7-fluoro-2H-1,4-benzoxazin-3(4H)-one, as an intermediate of 2-(7-fluoro-4-propargyl-2H-1,4-benzoxazin-3(4H)-on-6-yl)-4,5,6,7-tetrahydroisoindole, is useful as intermediate as a herbicide.